Tested on Android using Chrome, Opera, Firefox and Edge - the 'thumbnail' is displayed in all.
The availability of that image for the video is up to the browser - it's obtained via preloading of the metadata of the video, which gives it the first frame of the video as long as the browser isn't stopping the default preload functionality for the HTML5 <video> tag.
Invision's implementation doesn't include the preload attribute on the <video> tag, so it is up to the browser to decide what it wants to do as it isn't being told specifically.